Manganese doping generates oxygen vacancies to enhance the performance of cobalt oxyhydroxide in activating peroxymonosulfate

Abstract

A process for activating peroxymonosulfate using Mn-doped cobalt oxyhydroxide (CoOOH) was developed, achieving efficient removal of organic pollutant. Targeting sulfamethoxazole (SMX) as the pollutant, the reaction rate of cobalt hydroxide with a 10 % manganese doping (CoMn10) increased by more than tenfold compared to undoped CoOOH. Under conditions of 0.3 g/L catalyst and 0.5 mM PMS, 10 mg/L SMX was removed within 10 min. The activation of PMS to degrade SMX is mainly based on heterogeneous catalytic reaction. Quenching experiments, electron paramagnetic resonance spectra and methyl phenyl sulfoxide (PMSO) probe confirmed the presence of multiple reactive oxygen species in the CoMn10/PMS system, including sulfate radicals, singlet oxygen, high-valent metals, and electron transfer. It was resistant to multiple anions (Cl⁻, NO₃⁻, SO₄²⁻) and has catalytic stability in real water. CoMn10/PMS system has the ability to degrade a variety of pollutants efficiently. The introduction of manganese facilitates the formation of oxygen vacancies. The density functional theory (DFT) computation showed that manganese increased the adsorption energy and electron transport flux of CoOOH, enhanced the chemical activity of CoOOH, and the structure of PMS adsorbed on CoMn10 was more easily adsorbed and cleavaged.